1. Field of the Invention
The present invention relates generally to a semiautomatic slide mechanism, and more particularly to a semiautomatic slide mechanism applied to a portable electronic device.
2. Description of the Related Art
Following the development of various mobile techniques, different types of progressive portable electronic products have been developed. Also, users have more and more strictly required various lightweight, miniaturized, convenient-use and long-lifetime mobile electronic devices. Recently, large-size portable electronic products have become more and more popular. Such large-size portable electronic products are even more strictly required to have the above advantages. For example, many designs of the slide cover mechanism concept of a common slide cover mobile phone have been directly applied to the large-size portable electronic products such as tablet mobile phones and tablet computers. The slide cover mechanism of an early-stage mobile phone generally includes a slide board and a slide seat adapted to the slide board. The slide board is slidable relative to the slide seat. At least one elastic member is disposed between the slide board and the slide seat to provide elasticity between the slide board and the slide seat. The slide board is generally fixedly connected with a cover body, while the slide seat is fixedly connected with a main body. An operator can operate the slide board to slide relative to the slide seat. After the slide board slides by a certain distance, the elastic member stores elastic potential energy for the slide board to automatically slide to the end of the travel.
In the case that the currently most often seen slide cover mechanism is directly applied to a large-size tablet computer, personal digital assistants (PDA) or electronic book, it often takes place that the slide cover can be hardly smoothly slid due to over-tightening of the cooperative components. In some other cases, the slide cover will deflect during sliding due to too large gap between the components. In addition, with respect to the elastic member such as (torque spring) in the slide cover mechanism of the mobile phone, the elastic member is generally made of a small-diameter fine metal wire. In the case that such elastic member is directly applied to a large-size electronic device, the slide cover mechanism will have insufficient fatigue strength. After a period of use, the elastic member will deform or break due to elastic fatigue. This needs to be improved.
In order to solve the problems existing in the early-stage slide cover mechanism, another type of conventional slide cover mechanism has been developed. The slide cover mechanism includes a slide board and a slide seat. The slide seat is relatively slidably disposed on the slide board. The slide cover mechanism further includes a gear, two racks, an elastic member and an engagement body. The racks are respectively disposed on two sides of the slide board in different sliding travels. The gear is disposed between the slide board and the slide seat in cooperation with the racks. The slide board is formed with a slide slot. The slide seat is formed with a guide hole. The gear is formed with a shaft hole. One end of the engagement body is passed through the guide hole and the shaft hole of the gear and slidably engaged in the slide slot of the slide board. The elastic member can be a clockwork-type elastic member. One end of the elastic member is fixedly connected with the gear, while the other end of the elastic member is fixedly engaged with the engagement body. When an external force is applied to the slide seat to make the slide seat slide, the elastic member stores elastic potential energy with the rotation of the gear driven by the racks. After the gear rotates to separate from one of the racks, the gear further engages with the other rack. At this time, the elastic member releases the elastic potential energy conserved in the foregoing travel. In this case, the slide seat will automatically slide in the original sliding direction to the end of the travel, and vice versa.
In comparison with the early-stage conventional slide cover mechanism, the above slide cover mechanism adopts the gear and the cooperative racks and the elastic member wound between the gear and the engagement body passing through the guide hole of the slide seat. Accordingly, under external force, the gear can gradually wind up the elastic member to store elastic potential energy. In addition, under the guiding of the slide slot, the gear can move from one rack for the early half of the travel to the other rack for the later half of the travel. At the later stage of the travel, the elastic member releases the elastic potential energy conserved at the early stage of the travel to make the slide seat automatically continuously slide to the end of the travel.
However, in practice, it is found that the combination of the gear and the racks has a shortcoming as follows: The distance between the racks is designed to be larger than the diameter of the gear so as to avoid self-locking of the gear in the middle of the travel at the junction between the two-way racks or prevent the gear from failing to engage with the rack for the later half of the travel. Moreover, at the junction between the two racks, the slide slot is guided via a biased slot from a path distal to the rack for the early half of the travel to a path distal to the rack for the later half of the travel. Therefore, at the junction between the two racks, the gear will displace away from the rack for the early half of the travel to the rack for the later half of the travel. Accordingly, the gear can be more smoothly engaged with the racks. However, in practice, it is found that the elastic member often releases most of the elastic potential energy after the gear is disengaged from the rack for the early half of the travel but when not yet fully engaged with the rack for the later half of the travel. As a result, in operation, it often takes place that the slide cover cannot truly automatically slide to the end of the travel.